Electricity is indispensable to modern people in their everyday life. Normally, if people find the number of sockets at home is not enough, they may choose to plug an extension cord to a socket, such that they may plug several appliances to the sockets of the extension cord.
Normally, the upper power limit of an extension cord (for example, the upper limit of total current being 12 or 15 ampere (A)) is indicated on the extension cord. However, those who do not have a good knowledge of electricity still cannot easily understand current power consumption status of the extension cord despite having seen the indication of the upper limit of total current. Under such circumstance that the user is not aware of power consumption and overuses the extension cord, the power may be interrupted and electrical fire may be resulted.
Preferably, a socket, an extension cord or a charger capable of showing current power consumption or current charging status is provided to help those not having basic knowledge of electricity be aware of current power consumption or charging status.